Yaw rate control for electric vehicle with two-motor drive of front wheels
Students Name: Shevchuk Dmytro Serhiiovych
Qualification Level: master (ESP)
Speciality: Electrical Energetics, Electrical Engineering and Electromechanics
Institute: Institute of Power Engineering and Control Systems
Mode of Study: full
Academic Year: 2019-2020 н.р.
Language of Defence: ukrainian
Abstract: In the master’s qualification thesis, for the electric vehicle (EV) based on the Audi A2 car, the front-wheel drive design scheme with two on-board electric motors, one for each wheel, has beenchosen. The calculation of the parameters of traction electric drives was carried out based on the specified initial consumer parameters and technical characteristics of the car. According to the results of mathematical calculations, the rated motor power, torque, and speed were found. Based on them, the main parameters required for the implementation of the drive motor model were obtained using the model of vector control of a synchronous motor with permanent magnets in the Matlab/Simulink software. In this work, an electric scheme of the EM electric drive system with an electronic differential and the course stabilization system (CSS) was developed. The electronic differential system works based on the Ackermann-Jeantaud geometry. EM control system is two-level. Lower level controllers control closed-loop systems for regulating the electromagnetic torques of motors. The higher level controller performs the functions of electronic differential control and CSSof EV. Among the ways to implement the electronic differential, power steering control - a special control of wheels torques in the presence of a steering mechanical system was chosen. In this implementation, you can achieve a complete analogy with the usual driving, when the driver directly affects the angle of rotation and feels the impact of the vehicle on the steering column. In addition, the wheel torque control system also provides damping of mechanical oscillations that occur due to the elasticity of the elements of the steering system, as well as amplificationthe steering control. The results of computer simulation of the electronic differential control system confirm its operability. To determine the structure of the CSS and its study, a complete mathematical model of the dynamics of EM motion (7-DOF model of body motion) was built. The Pacejka model was used to describe the nonlinear dynamics of wheel motion. This model is based on experimental data and provides a method for calculating the longitudinal, lateral forces of the wheels and the equalizing torque for a wide range of vehicle operating conditions. The purpose of the CSS is to ensure the skid stability of the EV during the execution of the driver-set cornering at a given speed. Thanks to the ability to control the torques of the drive motors of the front wheels, the CSS sets an additional required value of the differential torque of the wheels, which compensates for the yaw torque and ensures the stability of the EM in its cornering. Two structures of the EVCSS of different complexity are proposed, built based on the analysis of regularities of dynamic behavior of a chassis and wheels in cornering. The mathematical model of EV control in the Matlab/Simulink softwareis created, on which the developed control systems is investigated. It is shown by computer simulation using the created model, as the yaw torque set by the CSS is worked out by the electric drive systems of the wheels. The thesis also describes the possibilities of using CarSim software for virtual modeling of different car systems and their behavior in different simulated situations in the development of EV control systems. Based on the results of the research, general conclusions were made.